1. Field of the Invention
The invention relates to mechanisms for adjusting the cutting height of a mower deck suspended from a driven vehicle.
2. Description of the Related Art
A first type of mower deck height adjustment mechanism provides a lever arm that extends upwardly from the vehicle to be pivoted by one of the operator's hands. The lever is typically rigidly coupled with a laterally extending shaft that pivots about its own axis as the operator shifts the lever. The shaft is coupled with a linkage that acts to raise and lower the deck as the shaft rotates while maintaining the deck in a level or horizontal position. A locking mechanism is provided for securing the lever, shaft or linkage in a particular position to fix the deck's operating height. The locking mechanisms may provide a button carried at the end of the lever arm that can be depressed by the thumb of the operator. Another type of locking mechanism resiliently biases the lever arm into a row of slots, such that the operator must pivot the lever arm laterally to disengage the lever arm from the slots. The operator then pivots the lever arm longitudinally to vary the height of the mower deck, and the lever arm springs back into engagement with one of the slots to secure it in place.
This first type of height adjustment mechanisms and locking mechanisms include an undesirably large number of parts, such as lubricated pivot bearings and biasing springs. The cost of manufacturing and assembling the mechanism is therefore relatively high. Also, the operation of the first type of height adjustment mechanism may be difficult for the operator to execute due to the handle's position with respect to the operator station.
A second type of conventional mower deck height adjustment mechanism provides a lift arm carried on the vehicle between and beneath the operator's legs such that the operator can grasp and lift the lift arm with both hands while seated on the vehicle. The lifting operation is therefore easily accomplished since the operator can use both hands to lift the lift arm. A locking mechanism may be positioned adjacent the lift arm such that the operator can release the locking mechanism while grasping the lift arm with both hands. These locking mechanisms typically include a tooth or member that is resiliently biased into engagement with a slotted plate. The operator engages a control that shifts the member out of the slot, and can then shift the lift arm to the desired operating height. The operator then releases the locking control to allow the member to again engage the slotted plate to secure the deck in position.
Many of the lift mechanisms according to the second type are relatively complex and therefore involve the use of a large number of parts. Spring mechanisms are typically utilized to bias the member into engagement with the slotted plate. Therefore these mechanisms are relatively costly to manufacture and assemble.
Therefore, it would be desirable to provide a mower deck lift mechanism that is simple in construction and requires the use of a relatively small number of parts. It would be desirable for a mechanism to allow adjustment of the mower deck height while maintaining the deck in level or horizontal position, and to allow the operator to lift the deck with both of his hands. It would be desirable to provide a locking or securement mechanism that is simple in construction, and that comprises relatively few parts so that the mechanism is inexpensive to manufacture and assemble.